One type of density change is mass over volume.
It's either 3.5 or 1.2
There would be more evidence spread out through space to be noticed by scientists and it seems like a stretch to go as far back as 4 billion years ago.
(I mean really? That much before the DINOSOURS died? I don't think so)
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Hope this helps
Miri
Answer:
Why are embryos used in medical research?
Stem cells can be obtained at the early stages of embryo development; these cells are called human embryonic stem cells (hESC). They also could be used in research to develop drugs to treat serious diseases, or to repair organs following a stroke or heart attack.
Answer: The nervous system of human body is responsible for thermoregulation.
Explanation:
Thermoregulation is the process whereby an organism maintain its internal temperature despite changes in External temperature. The nervous system of human body is responsible for thermo regulation. The nervous system consist of nerves cells and fibres which send nerves impulses to the body parts. It comprises of central nervous system and peripheral nervous system. The centsl nervous system consist of brain and spinal cord while the peripheral nervous system consist of nerves. A part of the brain (central nervous system)called hypothalamus controls thermo regulation. When it senses a change in internal temperature of the body, its send signals to the organs, muscles, glands and nervous system , they respond differently so as to restore the body temperature to its normal one.